Sn-Pt/Al DHe-2 Sn-Pt/Al CHe
4.1. Acidic Properties
4.3.2. Mechanism of Propylene Oxidation
4.3.3.3. Effect of Hydrogen Pretreatment
4.3.3.3.1. Proposed Mechanism over Hydrogen Treated Samples
Pt metal sites play an important role in cyclopropane isomerisation since the highest activity was observed for reduced Pt/Al among the catalysts studied. The isomerization of cyclic hydrocarbon over metal sites requires hydrogen as a co-catalyst (Du et al., 2005), (Bond and Newhan, 1960). It has been reported that hydrogenation of cyclopropane over platinum catalysts proceeds most probably in terms of Eley-Rideal mechanism when gas-phase or physically adsorbed cyclopropane reacts with chemisorbed hydrogen around or above 473 K (Bond and Newhan, 1960), (Addy and Bond 1957 ), (Bond and Sheridan, 1952).
Based on above mentioned the radical mechanism of cyclopropane isomerization over platinum metallic sites can be proposed over reduced Pt/Al catalyst. The schematic presentation of this mechanism is shown in Fig.33:
Fig. 33. Schematic presentation of radical mechanism of isomerization of cyclopropane over samples containing metallic platinum species
The first step is the formation of active hydrogen species during pretreatment in H2
by homolytical adsorption of hydrogen molecule in presence of metallic platinum. In second step cyclopropane is physically adsorbed on metal, which then reacts with chemisorbed hydrogen in push-pull manner (Du et al., 2005) to produce adsorbed alkyl radical. The adsorbed propyl radical may then either lose one hydrogen atom (isomerization process) and form propylene-product or attach a hydrogen atom (hydrogenation process) to form propane by-product. In our case the main product was propylene (99.3%) since the further hydrogenation of C3H6 was limited by presence of hydrogen (hydrogen was used for pretreatment of the surface before reaction starts and was absent in reacting mixture during reaction run). The situation could change with
excess of hydrogen, when H2 is present in reacting mixture. In this case hydrogenation of cyclopropane (Bond and Sheridan, 1952) could be the dominat reaction with formation of propane as the main product.
5. CONCLUSION
Addition of small amount of platinum (0.28 %) strongly influences the physico-chemical characteristics of tin containing catalyst with consequences on its catalytic behavior.
The deposition of SnO2 or platinum oxide alone enhances the number of the total acid sites (combining acid sites of support Al3+ and supported compounds Sn4+ and/or Ptn+) and their strength on catalyst surface. However, the simultaneous presence of platinum and tin oxides decreases the strength of stronger acid sites possibly due to the electron transfer from tin to platinum. This effect can be explained by Sn-Pt electronic interaction: SnO2, known as n-type semiconductor, can change the electronic density in the bulk by transmitting electrons to the PtO (p-type semiconductor) and Al2O3 (weak n-type semiconductor), and thus decreases the acidic strength of some of the corresponding Lewis sites.
Microcalorimetric study of CO adsorption showed that platinum ions are better dispersed on the surface of Sn-Pt/Althan for Pt/Al catalystsample. A higher dispersion of Pt in Sn-Pt/Alis probably the result of the dilution of platinum particles into smaller ensembles in presence of tin element.
FTIR study showed that Pt/Aland Sn-Pt/Alare promising catalysts for oxidation of carbon monoxide to carbon dioxide through carbonate and bicarbonate intermediates formation on the catalyst.
It was concluded that the studied catalysts were not active in selective oxidation (propylene : air ratio mixture 1:10) since CO2 (CO) and water were formed as a main products.
The deposition of the low surface area SnO2 on γ-alumina produced a catalyst with higher surface area but lower oxidation activity then pure bulk SnO2. Platinum containing catalysts showed good catalytic activity for total propylene oxidation (conversion of 95-100% at 673 K). Sn-Pt/Al sample showed the highest selectivity
the dissociative propylene adsorption and mobility of the surface lattice oxygen, as consequence it increases the rate of oxidation reaction. Additionally, FTIR results showed that the formation of Lewis acidic sites responsible for hydrocarbon oxidation proceeds at dehydroxylation temperature ≥ 573 K therefore relatively high activation reaction temperature is needed for oxidation of hydrocarbons.
In agreement with electrical conductivity results it was concluded that the c-C3H6
isomerization proceeds probably over Brönsted acid sites (via formation of C3H7+
intermediate) of oxidized samples. Since Lewis acidity was detected on the samples studied the possible involvement of the Lewis acid sites (via formation of C3H5+
intermediate) in cyclopropane isomerization could also be considered. Cyclopropane isomerization started at around 473 K and the increase of the reaction temperature (523 K) increased the reaction rate. The temperature increase up to 473 K for isomerization increased the proton mobility, i.e., the surface/bulk proton or hydride movement and thus reduced the strong adsorption of hydrocarbon species. The oxidized samples showed the following catalytic activity sequence for c-C3H6 isomerization at 523K:
Sn-Pt/Al > Pt/Al > Al > Sn/Al.
Only the Pt/Al exhibited high catalytic activity (k= 6.8·10-3 mol·g-1·s-1) and selectivity (nearly 100% of reacted cyclopropane was transformed to propylene) from reduced catalysts where isomerization probably takes place via the formation of the allyl radical intermediates.
From cyclopropane isomerization studies concluded that tin exists in different forms in Sn-Pt/Al, depending on the pretreatment conditions of the catalyst (i) in an oxidized form, Sn4+ (SnO2), resulting in a promoting effect; (ii) in reduced form, tin resulting poisoning effect “ligand-effect” due to blocking of the sites responsible for cyclopropane isomerizationby formation an alloy.
This research work has been started in the frame of an international research INCOCOPERNICUS research project ERBIC 15 CT 98 05 15. Within this project the Sn-Pt/Alwas recommended as a catalyst for total oxidation of lower hydrocarbons (C1 -C3) and also for environmental purposes (CO elimination). As an outcome thecatalyst system has been scaled up at industrial level at ROMPETROL, VEGA Refinery, Romania.
REFERENCES
Ai M., Ikawa I., (1975), The acid-base properties of MoO3-Bi2O3-P2O5 catalysts and their correlation with catalytic activity and selectivity, J.Catal., 40, 203-411.
Addy J., Bond G.C., (1957), Catalysis on metals of group 8. Part 1. Reaction of cyclopropane and of propane with deuterium over a palladium catalyst. Part 2. The reaction of deuterium with propylene and with propyl chlorides over a palladium catalyst. Part 3. The reaction of cyclopropane and of propane with deuterium over rhodium and iridium catalysts. Part 4. The reaction of cyclopropane and of propane with deuterium over a platinum catalyst, Trans.
Faraday Soc., 53, 368-392.
Amalric-Popescu D., Bozon-Verduraz F., (2001), Infrared studies on SnO2 and Pd/SnO2, Catal.
Today, 70, 139-154.
Anderson J., Rochester C., (1991), Infrared study of CO adsorption on Rt-Rh/Al2O3 catalysts, J.
Chem. Soc., Faraday Trans., 87 (9), 1479-1483.
Anderson A.A., (1992), Infrared study of the oxidation of carbon monoxide over Pt/Al2O3, J.
Chem Soc. Farady Trans., 88, 1197-1201.
Auroux A., (2000), Semiconductor Metal Oxides as High Performance for Energetically and Environmentally Improved Catalytic Combustion of C1-C3 Hydrocarbons, EU-Project, INCO ERBIC 15 CT 98 05 15, partner report
Auroux A., (1997), Acidity characterization by microcalorimetry and relationship with reactivity, Top.Catal., 4, 71-89.
Baba T., Ono Y., (1987), Hydrogen induced catalysis by silver-exchanged zeolites:
transformation of ethylbenzene over AgY zeolite, Zeolites, 7, 292-294.
Baird R.L., Aboderin A.A, (1964), Concerning the role of protonated cyclopropane
intermediates in solvolytic reactions. I. The solvolysis of cyclopropane in deuteriosulfuric acid, J. Am. Chem. Soc., 86, 252-255.
Balakrishnan K., Schwank J., (1991), A chemisorption and XPS study of bimetallic Pt-Sn/Al2O3
catalysts, J. Catal., 127, 287-306.
Baldwin T. R., Burch R., (1990), Catalytic combustion of methane over supported palladium catalysts : I. Alumina supported catalysts, Appl. Catal., 66, 337-358.
Ballinger T.H., Yates J.T., (1991), IR spectroscopic detection of Lewis acid sites and Al2O3
using adsorbed CO. Correlation with Al-OH group removal, Langmuir, 7, 3041-3045.
Barshad Y., Znou X., Gulari E., (1985), Carbon monoxide oxidation under transient condition:
a Fourier –Transform Infrared Transmission spectroscopy study, J. Catal., 94, 128-141.
Barth R., Pitchai R., Anderson R.L., Verykios X.E., (1989), Thermal Desorption-Infrared study of carbon monoxide adsorption by alumina-supported platinum, J. Catal., 116, 61-70.
Benson S.W., (1961), Reaction of cyclopropane with Iodine and some observations on the isomerization of cyclopropane, J. Chem. Phys., 34, 521-526.
Bettahar M. M., Costentin G., Savary L., J. C. Lavalley (1996), On the partial oxidation of propane and propylene on mixed metal oxide catalysts, Appl.Catal.A.,145, 1-48
Blyholder G., (1964), Molecular orbital view of chemisorbed carbon monoxide, J. Phys. Chem., 68, 2772-2778.
Bond G.C., Sheridan J., (1952), Studies in heterogeneous catalysis. Part 4. –The hydrogenation of cyclopropane, Trans. Faraday Soc., 48, 713-715.
Bond G.C., Newham J., (1960), Catalysis on metals of group VIII. Part 5.-The kinetics of the hydrogenation of cyclopropane and of methylcyclopropane, Trans. Faraday Soc., 56, 1501-1514.
Bordwell F. G., (1988), Equilibrium Acidities in Dimethyl Sulfoxide Solution, Acc. Chem. Res, 21, 456-463
Burrington J. D., Kartisek C. T., Grasselli R. K., (1984), Surface intermediates in selective propylene oxidation and ammoxidation over heterogeneous molybdate and antimonate catalysts,J.Catal.,87,363-380.
Caldararu M., Sprinceana D., Popa V.T., Ionescu N.I., (1996), Surface dynamics in tin dioxide-containing catalysts II. Competition between water and oxygen adsorption on polycrystalline tin dioxide, Sensors and Actuators B, 30, 35-41.
Caldararu M., Postole G., Hornoiu C., Bratan V., Dragan M., Ionescu N. I., (2001), Electrical conductivity of γ-Al2O3 at atmospheric pressure under dehydrating/hydrating conditions, Appl.
Surf. Sci., 181, 255-264.
Caldararu M., (2002), Semiconductor Metal Oxides as High Performance for Energetically and Environmentally Improved Catalytic Combustion of C1-C3 Hydrocarbons, EU-Project, INCO ERBIC15CT98 0515, final partner report
Caldararu M., Postole G., Carata M., Chelu M., Hornoiu C., Ionescu N., Juchakova T., Rédey Á., Auroux A. (2002), Electrical Behavior of γ-Al2O3 Supported Catalysts for Hydrocarbons Combustion. Paper presented to 3rd Conference of the Chemical Societies of the South-Eastern European Countries, Bucharest, Romania.
Caldararu M., Postole G., Carata M., Hornoiu C., Ionescu N. I., Ioujakova T., Redey A., (2003), Adsorption on transition aluminas from in situ capacitance measurements, Appl. Surf. Sci., 207, 318-326.
Caldararu M., Postole G., Carata M., Chelu M., Hornoiu C., Ionescu N. I., Juchakova T., Redey A., (2003), In situ electrical conductivity study of propylene interaction with alumina surface, Appl. Surf. Sci., 211, 156-165.
Carata M., Hornoiu C., Postole G., Caldararu M.,Ionescu N.I., Munteanu C., Jouchakova T., Redey A., (2004), Surface Characteristics of SnO2-Pt/γ-Al2O3 Oxidation Catalyst, Book of abstract, 13th International Congress on Catalysis, Paris, France, July 11-16.
Ciuparu D., Altman E., Pfefferle L., (2001), Contributions of lattice oxygen in methane combustion over PdO-based catalysts, J. Catal., 203, 64–74.
Ciuparu D., Pfefferle L., (2002), Contributions of lattice oxygen to the overall oxygen balance during methane combustion over PdO-based catalysts, Catal.Today, 77, 167–179.
Coq B., Figueras F., (1984), Conversion of methylcyclopentane on Platinum-Tin reforming catalysts, J. Catal., 85, 197-205.
Conner W. C., Falconer J. L., (1995), Spillover in heterogeneous catalysis, Chem. Rev., 95, 759-788.
Damyanova S., Bueno J. M. C., (2003), Effect of CeO2 loading on the surface and catalytic behaviors of CeO2-Al2O3-supported Pt catalysts, Appl. Catal. A, 253, 135-150.
Dautzemberg F.M., Helle J.N., Biloen P., Sachtler W.M.H., (1980), Conversion of n-hexane over monofunctional supported and unsupported PtSn catalysts, J. Catal., 63, 119-128.
Davidov A.A. (1984), IK spectroscopija v xumuu poverxcnoctu okuclov, Izdatelctvo “Nayka”, Novosibirck, 1984
Davis B.H., Westfall G.A., Watkins J., Pezzanite J., (1976), Paraffin dehydrocyclization : VI.
The influence of metal and gaseous promoters on the aromatic selectivity, J. Catal., 42, 247-256.
Dragoi B., Gervasini A., Dumitriu E., Auroux A .,(2004), Calorimetric determination of the acidic character of amorphous and crystalline aluminosilicates, Thermochim. Acta, 420, 127–
134.
Du H., Fairbridge C., Yang H., Ring Z., (2005), The chemistry of selective ring-opening catalysts; Review, Appl. Catal. A, 294, 1–21.
Dyne S.R., Butt J.B., Haller G.L., (1972), The structure and activity of chromium oxide catalysts. II Influence of catalyst structure on activity for reactions of cyclopropane, J. Catal., 25, 391-397.
Ebitani K., Konishi J., Hattori H., (1991), Skeletal isomerization of hydrocarbons over zirconium oxide promoted by platinum and sulfate Ion, J. Catal., 130, 257-267.
Emsley J., The elements, 2nd edition, Clarendon press, Oxford, 1991
Fejes P., Hannus I., Kiricsi I., Varga K., (1978), Investigation of the skeletal isomerization of cyclopropane on NaY modified by elementary Na, Acta Phys. et Chem. Szeged, 24, 119-30.
Gassman P.G., Johnson T.H., (1976), Retrocarbene additions. Dissection of alkyl-substituted cyclopropanes under metathesis conditions, J Amer .Chem. Soc., 98, 6057-6058.
Gassman P.G., Johnson T.H., (1977), The relationship of polarization in metal-carben complexes to the degenerate metathesis of terminal olefins, J Amer .Chem. Soc., 99, 622-623.
George Z.M., Habgood H.W., (1970), Mechanism of the isomerization of cyclopropane over Brönsted acid catalysts, J. Phys. Chem., 74, 1502-1508.
Gergely B., Rédey Á., Guimon C., Gervasini A., Auroux A., (1999), Microcalorimetric studies of the surface reactivity of pollutant gas atmospheres on supported SnO2 and Ga2O3 catalysts, J. Therm. Anal. Cal., 56, 1233-1241.
Goldwasser J., (1981), Studies of reactions of butenes and cyclopropanes catalyzed by oxides, PhD Diss, The University of Wisconsin-Milwaukee, USA.
Gordimova T.A., Davidov A.A., (1979), Spectroscopic study of propylene complexes formed on γ-alumina surface, isomerization mechanisms, Dokladi Akademii Nauk S.S.S.R., 245, 623-639.
Grotthuss C.J.T., (1806), Sur la décomposition de l'eau et des corps qu'elle tient en dissolution à l'aide de l'électricité galvanique, Ann. Chim. (Paris), 58, 54-73.
Guerrero-Ruiz A., Maroto-Valiente A., Cerro-Alarcón M., Bachiller-Baeza B., Rodriguez-Ramos I., (2002), Surface properties of supported metallic clusters as determined by microcalorimetry of CO chemisorption, Top. Catal., 19, 303-311.
Guimon C., Gervasini A., Auroux A., (2001), XPS study of the adsorption of SO2 and NH3 over supported tin dioxide catalysts used on de-Nox catalytic reaction, J. Phys.Chem. B, 105, 10316-10325.
Hagen J., Industrial catalysis: a practical approach, WILEY-VCH, 1999
Hall W.K, Lutinski F.E., Gerberich H.R., (1964), Studies of the hydrogen held by solids. IV The hydroxyl groups of alumina and silica-alumina as catalytic sites, J. Catal., 3, 512-527.
Harbeck S., Szatvanyi A., Barsan N., Weimar U., Hoffmann V., (2003), DRIFT studies of thick film un-doped and Pd-doped SnO2 sensors: temperature changes effect and CO detection mechanism in the presence of water vapor, Thin Solid Films, 436, 76-83.
Harrison P.G., (1987), Chemistry of Tin. 12. Tin (IV) Oxide: Surface Chemistry, Catalysis and Gas Sensing, Black key, 397-420.
Harrison P., Guest A., (1987), Tin Oxide Surfaces Part 17.- Infrared and thermogravimetric analysis of termal dehydration of Tin (IV) oxide gel, J. Chem. Soc., Faraday Trans.1, 83(11), 3383-3397.
Harrison P., Guest A., (1989), Tin oxide surfaces part 18.- Infrared Study of the adsorption of very low levels (20-50 ppm) of carbon monoxide in air on to Tin (IV) oxide gel. J. Chem. Soc., Faraday Trans.1, 85(8), 1897-1906.
Herz R.K., (1989), CO-Oxidation Catalysts: Low-Temperature CO Oxidation Covers Noble-Metal Reducible-Oxide (NMRO) Catalysts, Proceedings of the NASA International Conference, NASA Conference Publication, Hampton, No 3076, 21-40.
Hightower J.W., Hall W.K., (1968), Tracer studies of acid-catalyzed reaction. VII. Mechanism of alkylcyclopropane isomerization over silica-alumina, J. Am. Chem. Soc., 90, 851-858.
Hightower J.W., Hall W.K., (1968), Tracer Studies of Acid-Catalyzed Reaction. VIII. Langmuir Kinetics in Cycloalkane Isomerization, J. Phys. Chem., 72, 4555-4562.
Irving E. A., Taylor, D., (1978), Acidic properties of mixed tin-antimony oxide catalysts, J.
Chem. Soc., Faraday Trans. 1, 74, 206-210.
Jacono M.L., Hall W.K., (1977), Catalysis and surface chemistry. I. Cyclopropane reactions over reduced molybdena- alumina, J. Colloid Interf. Sci., 58, 76-87.
Keulks G.W., (1970), The mechanism of oxygen atom incorporation into the products of propylene oxidation over bismuth molybdate,J.Catal., 19, 232-235.
Kiricsi I., Hannus I., Varga K., Fejes P., (1980), Reaction of cyclopropane over zeolite catalysts, J. Catal., 63, 501-504.
Kirszenszejn P., Przystajko W., Bell T.N., (1993), Al2O3-SnO2 systems as a support for metallic catalysts. III. Acid-base properties of modified aluminas, Catal. Lett., 18, 391-399.
Knözinger. H., Ratnasamy P., (1978), Catalytic aluninas: surface models and characterization of surface sites, Catal. Rev.- Sci. Eng., 17, 31-70.
Kodama S., Yabuta M., Anpo M., Kubokawa Y., (1985), Photocatalytic isomerization of butenes over ZnO and SnO2, Bull. Chem. Soc. Jpn., 58, 2307-2310.
Krenzke L. D., Keulks G.W., (1980), The catalytic oxidation of propylene : VI. Mechanistic studies utilizing isotopic tracers, J.Catal.,61, 316-325.
Krenzke L. D., Keulks G.W., (1980), The catalytic oxidation of propylene : VIII. An
investigation of the kinetics over Bi2Mo3O12, Bi2MoO6, and Bi3FeMo2O12, J.Catal.,64, 295-302.
Kreuer K.D., (1996), Proton Conductivity: Materials and Applications, Chem.Mater. 8, 610- 641
Kulkarni D., Wachs I. E., (2002), Isopropanol oxidation by pure metal oxide catalysts: number of active surface sites and turnover frequencies, Appl. Catal., A237, 121-137.
Kung H.H., (1989), Studies in Surface Science and Catalysis: Transition Metal Oxides: Surface Chemistry and Catalysis, 45, Elsevier, Amsterdam Oxford New York Tokyo, 121-136.
Kustov L.M., (1997), New trends in IR-spectroscopic characterization of acid and basic sites in zeolites and oxide catalysts, Top. Catal., 4, 131-144.
Larson J. G., Gerberich H. R., Hall W. K., (1965), Tracer studies of acid-catalyzed reactions. I. The isomerization of cyclopropane over silica-alumina, J. Am. Chem. Soc, 87, 1880-1889.
Lieske H., Lietz G., Spindler H., Völter J., (1983), Reactions of platinum in oxygen- and hydrogen-treated Pt/γ-Al2O3 catalysts: I. Temperature-programmed reduction, adsorption, and redispersion of platinum, J.Catal., 81, 8-16.
Lieske H., Völter J., (1984), State of Tin in Pt-Sn/Al2O3 reforming catalysts investigated by TPR and chemisorption, J. Catal., 90, 96-105.
Lietz G., Lieske H., Spindler H., Hanke W., Völter J., (1983), Reactions of platinum in oxygen- and hydrogen-treated Pt/γ−Al2O3 catalysts. II Ultraviolet-visible studies, sintering of platinum, and soluble platinum, J. Catal., 81, 17-25.
Linsen B.G., (1970), Physical and Chemical Aspects of Adsorbents and Catalysis, Chapter 4 Active Alumina, Academic Press, London New York, 171-208.
Lombardo E.A., Jakono M.L., Hall W.K., (1978), Tracer studies of cyclopropane reactions on molybdena-alumina catalysts, J. Catal., 51, 243-255.
Manoiu D., Ionescu M., (2002), Semiconductor Metal Oxides as High Performance for Energetically and Environmentally Improved Catalytic Combustion of C1-C3 Hydrocarbons,
Margitfalvi J., Hegedüs M., Gőbölös S., Kern-Tálas E., Szedlacsek P., Szabó S., Nagy F., (1984), Controlled Surface Reactions for Preparation of Sn-Pt/Al2O3 Catalysts, In Proceedings of the VIII-th International Congress of Catalysis, ed. G. Ertl, Verlag Chemie, Weinheim, IV, 903-914.
McAleer J.F., Moseley P.T., Norris J.O., Williams D.E., (1987), Tin dioxide gas sensors.
Part.1.Aspects of the surface chemistry revealed by electrical conductance variations, J. Chem.
Soc., Faraday Trans. I, 83, 1323-1346
Morterra C., Emanuel C., Cerrato G., Magnacca G., (1992), Infrared study of some surface properties of Boehmite (γ-AlO2H), J. Chem. Soc., Faraday Trans., 88, 339-348.
Muller A.C., Engelhard P.A., Weisang J.E., (1979), Surface study of platinum-tin bimetallic reforming catalysts, J. Catal., 56, 65-72.
Niwa M., Murakami Y., (1972), Study on olefin oxidation by periodic-pulse technique : I.
Propylene oxidation into acrolein using various oxide catalysts, J.Catal., 26, 359-369
Oliveros I., Pérez Zurita M. J., Scott C., Goldwasser M. R., Goldwasser J., Rondón S., Houalla M., Hercules D. M., (1997), The isomerization of cyclopropane over reduced molybdena–
alumina catalysts, J Catal, 171, 485-489.
Parkyns N.D., (1967), Surface properties of metal oxides. Part I. Infrared studies of the adsorption and oxidation of carbon monoxide on alumina, J. Chem. Soc. (A), 1910-1913.
Peacock J. M., Parker A. J., Ashmore P. G. , Hockey J. A., (1969) The oxidation of propene over bismuth oxide, molybdenum oxide, and bismuth molybdate catalysts : IV. The selective oxidation of propene, J.Catal.,15,398-406.
Reddy B., Khan A., Yamada Y., Kobayashi T., Loridant S., Volta J.C., (2003), Structural characterization of CeO2-MO2 (M=Si4+, Ti4+, Zr4+) mixed oxides by Raman spectroscopy, X-ray photoelecton spectroscopy, and other techniques, J. Phys. Chem. B , 107, 11475-11484.
Roberts R. M., (1959), Catalytic Isomerization of Cyclopropane, J. Phys. Chem., 63, 1400-1403.
Román-Martínez M.C., Cazorla-Amorós D., Yamashita H., de Miguel S., Scelza O.A., (2000), XAFS study of dried and reduced PtSn/C catalysts: nature and structure of the catalytically active phase, Langmuir, 16, 1123-1131.
Rosynek M.P, (1972), Catalytic alumina. Its Dual-site hature in isomeriszation and deuterium exchange reactions of unsaturated hydrocarbons, Ph.D. Diss., Rice University, Houston, Texas, USA.
Ryczkowski J., (2001), IR spectroscopy in catalysis, Catal. Today, 68, 263-381.
Scofield J. H., (1976), Hartree-Slater subshell photoionization cross-sections at 1254 and 1487 eV, J. Electron Spectrosc. Relat. Phenom., 8, 129-137.
Segawa K., Hall W.K., (1982), Catalysis and surface chemistry. III. The adsorption of pyridine on molybdena-alumina catalysts, J. Catal., 76, 133-143.
Serrano-Ruiz J.C., Huber G.W., Sánchez-Castillo M.A., Dumesic J.A., Rodríguez-Reinoso F.
Sepúlveda-Escribano A., (2006), Effect of Sn addition to Pt/CeO2–Al2O3 and Pt/Al2O3 catalysts:
An XPS, 119Sn Mössbauer and microcalorimetry study, J. Catal., 241, 378-388.
Shen J., Cortright R.D., Chen Y., Dumesic., (1994), Microcalorimetric and Infrared spectroscopic studies of γ-Al2O3 modified by tin oxides, Catal. Lett., 26, 247-257.
Simon M.W., Bennett C.O., Suib S.L., (1994), Cyclopropane reaction over Brönsted, cation, and meal sites in Ni/NaX Zeolites, J. Catal., 148, 100-112.
Siri G.J., Ramallo-Lopez J.M., Casella M.L., Fierro J.L., Requejo F.G., Ferretti O.A., (2005), XPS and EXAFS study of supported PtSn catalysts obtained by surface organometallic chemistry on metals. Application to the isobutene dehydrogenation, Appl. Catal. A, 278, 239-249.
Skoog D. A., Leary J.J., (1992), Principles of Instrumental Analysis, 4th edition, Harcourt Brace College Publishers, 1-700.
Sohlberg K., Pennycook S.J., Pantelides S.T., (2000), The bulk and surface structure of γ-Alumina, Chem. Eng. Comm., 181, 107-135.
Speller S., Bardi U., Surface Alloys and Alloy Surfaces: The Platinum-Tin System.
Chapter 4 in: The Chemical Physics of Solid Surfaces, Volume 10: Alloy surfaces and surface alloys; ed. by. D. P. Woodruff, Elsevier 2002, ISBN 0-444-51152-0.
Spivey J.J., Roberts G.W., (2004), Catalysis, Vol.17, The Royal Society of Chemistry, UK, 1-104.
Stoica M., Caldararu M., Capritza A., Ionescu N.I., (1996), Effect of some parasite surface reactions on the variation of electrical conductance in the H2−Pt/Al2O3 system, React. Kinet.
Catal. Lett., 57, 81-86.
Stoica M., Caldararu M., Rusu F., Ionescu N. I., (1999), Some experimental evidences for hydrogen spillover on Pt/Al2O3 catalysts by electrical conductivity transient response, Appl.
Catal. A, 183, 287-293.
Stoica M., Caldararu M., Ionescu N.I., Auroux A., (2000), Protonic conductivity of Pt/Al2O3 in hydrogen- and water-containing atmospheres, Appl. Surf. Sci., 153, 218-222.
Sullivan D.H., Conner W.C., Harold M.P., (1992), Surface analysis with FTIR Emission spectroscopy, Appl. Spectros., 46, 811-818.
Szabo Z., Kallo D., (1976), Contact Catalysis, Akadémiai Kiadó, Budapest, Vol. 1, 2.
Tanaka K., Okuhara T., (1980), A general aspect of catalytic hydrogenation and isomerization reactions on oxide catalyst. Characteristics of the reactions via ionic and nonionic
intermediates, J. Catal., 65, 1-8.
Thomas S., Sherwood P. M. A., (1992), Valence band spectra of aluminum oxides, hydroxides, and oxyhydroxides interpreted by X-alpha calculations, Anal.
Chem., 64, 2488-2495.
Thornton E.W., Harrison P.G., (1975), Tin oxide surface. Part 1. Surface hydroxyl groups and the chemisorption of carbon dioxide and carbon monoxide on Tin(IV) oxide, J. Chem. Soc.,
Faraday Trans 1, 71, 461-472.
Tsyganenko A.A., Mardilovich P.P, (1996), Structure of alumina surface, J. Chem. Soc., Faraday Trans., 92, 4843-4852.
Turek A.M., Wachs I.E., (1992), Acidic Properties of Alumina-Supported Metal Oxide Catalysts: An Infrared Spectroscopy Study, J. Phys. Chem., 96, 5000-5007.
Verbeek H., Sachtler W.M.H., (1976), The study of the alloy of platinum an tin by chemisorption, J. Catal., 42, 257-267.
Vértes C., Tálas E., Czakó-Nagy I., Ryczkowski J., Göbölös S., Vértes A., Margitfalvi J.
(1991), Mössbauer spectroscopy studies of Sn-Pt/Al2O3 catalysts prepared by controlled surface reactions, Appl. Catal., 68, 149-159.
Wallin M., Grönbeck H., Lloyd Spetz A.,. Skoglundh M., (2004), Vibrational study of ammonia adsorption on Pt/SiO2, Appl. Surf. Sci., 235, 487-500.
Wang G., Tattori H., Tanabe K., (1983), Acid-base and catalytic properties of ZnO2-SnO2,
Wang G., Tattori H., Tanabe K., (1983), Acid-base and catalytic properties of ZnO2-SnO2,